KR20180030855A - White-reflecting film for large-scale display - Google Patents

Abstract

And to provide a white reflective film which has excellent reflective properties and is hardly thermally warped. This problem is solved by a white reflective film having a reflective layer A, wherein the reflective layer A comprises: a. The content of the calcium carbonate particles is 10% by mass to 70% by mass with respect to the mass of the thermoplastic resin composition A1; or b. The thermoplastic resin composition contains the calcium carbonate particles in the thermoplastic resin A; And a thermoplastic resin composition A2 containing calcium carbonate particles and a resin for emergency use in the thermoplastic resin A. The content of the calcium carbonate particles is 5% by mass to 69% by mass with respect to the mass of the thermoplastic resin composition A2, By mass based on the total mass of the thermoplastic resin composition A2 and the content of the resin for emergency use is 1% by mass to 40% by mass with respect to the mass of the thermoplastic resin composition A2, and the total content of the calcium carbonate particles and the non- And 10% by mass to 70% by mass of the calcium carbonate particles, and the calcium carbonate particles have an average particle diameter of 0.1 to 1.2 占 퐉 and a 10% volume particle diameter D10, 50% (D90 - D10) / D50 ≤ 1.6, and the reflectance of the film is 60% or more. .

Description

WHITE-REFLECTING FILM FOR LARGE-SCALE DISPLAY BACKGROUND OF THE INVENTION [0001]

The present invention relates to a white reflective film for a large display which can be preferably used as a reflector.

In the planar light source, a reflector is disposed on the back surface, and the light from the light source is reflected to the front by the reflector to increase the light extraction efficiency and improve the brightness.

For example, in a backlight unit of a liquid crystal display device (hereinafter also referred to as LCD), a direct type having a light source and a reflective film on the back surface of the liquid crystal display panel, There is an edge light type in which a light source is provided on a side surface of such a light guide plate. Conventionally, CCFL has been widely used as a light source. In recent years, a light emitting diode (hereinafter also referred to as an LED) has been used for reducing power and thinning, and an edge light type LED backlight or a direct type LED backlight is mainstream . The edge light type backlight has an advantage that the LCD can be made thinner, while the direct type LED backlight is low in cost because it does not use the light guide plate.

The planar light source is also used as illumination for brightening the inside and outside of the room.

As the reflector, for example, a void-containing film formed by adding an inorganic particle or a non-resin to a thermoplastic resin such as polyester and forming a void therein by stretching it is often used (Patent Documents 1 to 5).

However, such a reflection plate may be deformed and warped due to heat or humidity from a light source or an external environment (hereinafter, such deflection may be referred to as " thermal bending "). When the reflector is warped, the brightness of the surface light source is uneven. For example, in the case of the LCD, the brightness of the screen is uneven.

In order to solve such a problem of thermal bending, Patent Document 6 proposes an idea of making it difficult for unevenness of brightness to be caused by warping by using a reflective surface formed with a metal layer on the uneven surface by particles. Further, studies have been made to improve the warping of the reflector by supporting the reflector by forming protrusions on the bottom surface member of the LCD (Patent Document 7) or by inserting a slit for absorbing the warp on the reflector (Patent Document 8). However, all these processes are costly.

Japanese Patent Application Laid-Open No. 2004-330727 Japanese Laid-Open Patent Publication No. 2011-11370 Japanese Laid-Open Patent Publication No. 2011-232369 Japanese Laid-Open Patent Publication No. 2013-88715 Japanese Laid-Open Patent Publication No. 2013-88716 Japanese Patent Application Laid-Open No. 2002-100227 Japanese Laid-Open Patent Publication No. 2013-229185 Japanese Laid-Open Patent Publication No. 2014-22060

The large-sized display has depressed portions for providing a circuit board or the like in the back chassis. The inventors of the present invention have found out that heat is easily retained in such depressed portion, and the problem of thermal bending becomes more conspicuous by such heat, and the inventors have paid attention to this.

SUMMARY OF THE INVENTION In consideration of the above background, it is an object of the present invention to provide a white reflective film which has excellent reflection characteristics and is hardly thermally warped even when used in a large display.

The inventors of the present invention have focused on the fact that the presence of voids in the void-containing film makes it easier to cause thermal deflection. However, simply reducing the void is undesirable in the direction in which the reflection characteristic is reduced. It was also noted that, depending on the weight of the inorganic particles as the void-forming agent, thermal bending easily occurs when it is heavy.

That is, the present invention adopts the following constitution in order to achieve the above object.

1. A white reflective film having a reflective layer A,

The reflective layer (A)

a. The content of the calcium carbonate particles is 10 mass% or more and 70 mass% or less with respect to the mass of the thermoplastic resin composition A1, and the thermoplastic resin A is composed of the thermoplastic resin composition A1 containing calcium carbonate particles,

or,

b. And a thermoplastic resin composition A2 containing calcium carbonate particles and an emulsion resin in the thermoplastic resin A. The content of the calcium carbonate particles is 5 mass% or more and 69 mass% or more with respect to the mass of the thermoplastic resin composition A2 % Of the total amount of the calcium carbonate particles and the content of the nonconstituent resin is not less than 1% by mass and not more than 40% by mass with respect to the mass of the thermoplastic resin composition A2, and the total amount of the thermoplastic resin composition A2 Is not less than 10% by mass and not more than 70% by mass with respect to the mass of the composition.

Wherein the calcium carbonate particles have an average particle diameter of 0.1 占 퐉 or more and 1.2 占 퐉 or less and a 10% volume particle diameter D10, a 50% volume particle diameter D50, and a 90% volume particle diameter D90 integrated from the minor diameter side are (D90 - D10) / D50 Lt; / RTI >

A white reflective film for a large display having a reflectance of at least 60%.

2. The reflective layer A comprises: a. The white reflective layer according to 1 above, wherein the thermoplastic resin A is composed of the thermoplastic resin composition A1 containing calcium carbonate particles and the content of the calcium carbonate particles is not less than 10% by mass and not more than 70% by mass with respect to the mass of the thermoplastic resin composition A1. film.

3. The reflective layer A is b. And a thermoplastic resin composition A2 containing calcium carbonate particles and an emulsion resin in the thermoplastic resin A. The content of the calcium carbonate particles is 5 mass% or more and 69 mass% or more with respect to the mass of the thermoplastic resin composition A2 % Of the total amount of the calcium carbonate particles and the content of the nonconstituent resin is not less than 1% by mass and not more than 40% by mass with respect to the mass of the thermoplastic resin composition A2, and the total amount of the thermoplastic resin composition A2 Is not less than 10% by mass and not more than 70% by mass with respect to the mass of the white reflective film.

4. The reflective layer A and the surface layer C on at least one surface,

The surface layer C is composed of a thermoplastic resin composition C containing surface layer particles and the surface layer particles thereof have an average particle diameter of 2.0 mu m or more and 50.0 mu m or less and a content of not less than 3% by volume with respect to the volume of the thermoplastic resin composition C , And 50% by volume or less, based on the total mass of the white reflecting film.

5. The white reflecting film according to any one of 1 to 4 above, wherein the thermoplastic resin A is a copolymerized polyethylene terephthalate.

6. The white reflective film as described in 5 above, wherein the copolymerization amount of the copolymerized polyethylene terephthalate is 1 mol% or more and 20 mol% or less based on 100 mol% of all the acid components of the copolymerized polyethylene terephthalate.

7. The white reflective film according to any one of 1 to 6 above, wherein a ratio of the thickness of the reflective layer A to a thickness of 100% of the white reflective film is 50% or more.

8. The white reflecting film according to any one of 1 to 7 above, further comprising a support layer B comprising thermoplastic resin B or thermoplastic resin composition B.

9. A surface light source using the white reflecting film according to any one of 1 to 8 above.

On the other hand, in Patent Document 1, barium sulfate having a small standard deviation of particle size distribution is used, and barium sulfate has a specific gravity so heavy that thermal bending is apt to occur. Patent Documents 2 to 5 disclose that although calcium carbonate particles are used and the ratio D90 / D10 of the 90% volume particle diameter D90 and the 10% volume particle diameter D10 is disclosed, in reality, Were not reviewed. In addition, there is no awareness of the issue of heat tolerance, and no consideration has been made from such a point of view.

INDUSTRIAL APPLICABILITY According to the present invention, a white reflective film having excellent reflective characteristics and being less prone to thermal bending even when used in a large-sized display can be provided.

1 is a schematic view showing a constituent used in a patch evaluation according to the present invention.
The sign
1: Chassis
2: Laminate of white reflective film, light guide plate, optical sheet
3: Equivalent to an equilateral triangle
4: Chu

In the white reflecting film of the present invention,

(Mode a) The thermoplastic resin A is provided with a reflection layer A composed of the thermoplastic resin composition A1 containing a specific form of calcium carbonate particles,

(Mode b) The thermoplastic resin A has a reflective layer A composed of a thermoplastic resin composition A2 containing calcium carbonate particles of a specific mode and a resin (hereinafter referred to as an emergency resin in some cases) for the thermoplastic resin A.

Hereinafter, each component constituting the present invention will be described in detail.

[Reflective Layer A]

The reflective layer A in the present invention is composed of the thermoplastic resin composition A1 containing the calcium carbonate particles in the thermoplastic resin A or the thermoplastic resin composition A2 containing the calcium carbonate particles and the nonconstituent resin in the thermoplastic resin A, The calcium particles and / or the nonrecipitating resin function as a void-forming agent to contain voids in the layer and to exhibit white color. Further, the thermoplastic resin composition A1 and the thermoplastic resin composition A2 are sometimes combined to form the thermoplastic resin composition A in some cases. The reflective layer A exerts a reflecting function by such voids. The reflectance of the reflective layer A at a wavelength of 550 nm is preferably 80% or more, more preferably 90% or more, particularly preferably 95% or more. This makes it easy to set the reflectance of the white reflecting film within a preferable range.

As described above, the reflective layer A has voids in the layer. However, it is preferable that the volume occupied by the volume of voids in the reflective layer A, that is, the void volume ratio is not less than 15% by volume and not more than 70% by volume. With such a range, the effect of improving the reflectance can be increased, and the reflectance as described above can be easily obtained. In addition, the effect of enhancing the stretch film-forming property can be enhanced. When the void volume ratio is too low, a desired reflectance tends to be hardly obtained. From this point of view, the void volume ratio in the reflective layer A is more preferably 30% by volume or more, particularly preferably 40% by volume or more. On the other hand, if it is too high, the effect of improving the stretch film-forming property tends to be lowered. From this point of view, the void volume ratio in the reflection layer A is more preferably 65% by volume or less, particularly preferably 60% by volume or less.

The void volume ratio can be achieved by adjusting the size and amount of the calcium carbonate particles in the reflection layer A and the kind and amount of the nonconforming resin.

(Thermoplastic resin A)

As the thermoplastic resin A constituting the reflective layer A, for example, a thermoplastic resin composed of polyester, polyolefin, polystyrene and acrylic can be mentioned. Among them, polyester is preferable from the viewpoint of obtaining a white reflective film excellent in mechanical properties and thermal stability.

As such a polyester, it is preferable to use a polyester comprising a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component include a terephthalic acid component, an isophthalic acid component, a 2,6-naphthalenedicarboxylic acid component, a 4,4'-diphenyldicarboxylic acid component, an adipic acid component and a sebacic acid component. . Examples of the diol component include an ethylene glycol component, a 1,4-butanediol component, a 1,4-cyclohexanedimethanol component, and a 1,6-hexanediol component. Among these polyesters, aromatic polyesters are preferable, and polyethylene terephthalate is particularly preferable. The polyester and preferably polyethylene terephthalate may be a homopolymer. However, from the viewpoint that the crystallization is inhibited when the film is uniaxially or biaxially stretched and the effect of improving the film forming property of the film is enhanced, the copolymerized polyester and furthermore, the copolymerized polyethylene terephthalate . As the copolymerization component, there may be mentioned the dicarboxylic acid component and the diol component, but an isophthalic acid component and a 2,6-naphthalenedicarboxylic acid component are preferable from the viewpoint of high heat resistance and high effect of improving the stretch film-forming property . The content of the copolymerization component is, for example, not less than 1 mol%, preferably not less than 2 mol%, more preferably not less than 3 mol%, particularly preferably not less than 2 mol%, based on 100 mol% of the entire dicarboxylic acid component of the polyester , For example, 20 mol% or less, preferably 18 mol% or less, more preferably 15 mol% or less, and particularly preferably 11 mol% or less. When the ratio of the copolymerization component is within this range, the effect of improving the film forming property of the film is excellent. In addition, the thermal dimensional stability is excellent. Further, the effect of suppressing thermal bending can be further improved.

Such a thermoplastic resin A preferably has a melting point of 200 캜 or more and 280 캜 or less. This makes it easier to suppress the thermal bending. If it is too low, the effect of suppressing thermal bending tends to be lowered, while if it is too high, the handling tends to be difficult. From this viewpoint, it is more preferably 205 DEG C or higher, more preferably 210 DEG C or higher, still more preferably 275 DEG C or lower, still more preferably 265 DEG C or lower.

The thermoplastic resin A constituting the reflective layer A in the present invention may be a mixture of a polyester as a preferable thermoplastic resin and another thermoplastic resin different from the polyester.

(Calcium carbonate particles)

In the present invention, the reflection layer A contains calcium carbonate particles having a specific aspect as a void-forming agent.

The calcium carbonate particles in the present invention have an average particle diameter of 0.1 占 퐉 or more and 1.2 占 퐉 or less and (D90-D10) / D50 of 1.6 or less. Here, D10, D50, and D90 are 10% volume particle diameter, 50% volume particle diameter, and 90% volume particle diameter, respectively, which are accumulated from the small diameter side of the calcium carbonate particles. By employing the calcium carbonate particles of this embodiment, it is possible to suppress thermal bending while having a high reflectance. That is, when coarse voids are present, thermal bending is likely to occur. By adopting calcium carbonate particles having a small average particle size and a sharp particle size distribution, relatively small voids (hereinafter referred to as micro voids) It is an aspect of the film which exists in a large number, and suppresses thermal warping by the coarse void. When the particle size distribution is broad, coarse particles are present, and coarse voids are likely to be formed. At the same time, the reduction in the amount of the interface between the void and the thermoplastic resin can be suppressed, and a high reflectance can be obtained. Further, since the calcium carbonate particles have a relatively small specific gravity, the mass difference or the difference in density between the particles and the thermoplastic resin is small, so that a local density difference at portions other than the voids is unlikely to occur. Whereby thermal bending is also suppressed.

If the average particle diameter of the calcium carbonate particles is too large, coarse voids tend to be formed, and thermal bending can not be suppressed. Therefore, the average particle diameter is preferably 1.1 占 퐉 or less, more preferably 1.0 占 퐉 or less, still more preferably 0.95 占 퐉 or less, particularly preferably 0.9 占 퐉 or less. On the other hand, even if it is too small, the particles aggregate together to form a coarse void, and it is very difficult to obtain such calcium carbonate particles. From this point of view, the average particle diameter is preferably not less than 0.3 占 퐉, more preferably not less than 0.5 占 퐉, and still more preferably not less than 0.6 占 퐉.

In other embodiments, when the average particle diameter of the calcium carbonate particles is too large, it is difficult to suppress the thermal bending. On the other hand, if the average particle diameter is too small, the coarse aggregate tends to form coarse voids, The balance of improvement of the reflectance and the cost, and there is also a case that it is preferable to be somewhat large. From such a viewpoint, the average particle diameter of the calcium carbonate particles is preferably 1.2 占 퐉 or less, more preferably 1.18 占 퐉 or less, further preferably 1.15 占 퐉 or less, further preferably 0.6 占 퐉 or more, More preferably 1.01 mu m or more, particularly preferably 1.02 mu m or more, and most preferably 1.05 mu m or more.

(D90 - D10) / D50 is preferably small in view of the above-mentioned point, more preferably not more than 1.5, still more preferably not more than 1.4. The lower limit is theoretically zero, and it is preferable that the lower limit is practically 0.1 or more.

In order to satisfy the above-described aspect, it is particularly preferable to employ particles made of synthetic calcium carbonate (hereinafter sometimes referred to as synthetic calcium carbonate particles) as the calcium carbonate particles in the present invention. Examples of the calcium carbonate particles include particles made of natural calcium carbonate (hereinafter sometimes referred to as natural calcium carbonate particles) and synthetic calcium carbonate particles, and natural calcium carbonate particles are usually used. However, the natural calcium carbonate particles tend to be difficult to satisfy the above-mentioned aspect, and it tends to be difficult to achieve the object of the present invention.

As the method of containing the calcium carbonate particles in the polyester resin, various conventionally known methods can be used. As a typical method, there may be mentioned the following methods.

(A) a step of esterification in the synthesis of the polyester resin or a method in which the esterification is carried out after completion of the transesterification reaction.

(B) a method of adding to the obtained polyester resin and melt-kneading.

(C) A master pellet obtained by adding a large amount of calcium carbonate particles to a polyester resin in the above (a) or (b) is prepared, and this and a polyester resin as a diluting polymer are kneaded, Wherein the calcium carbonate particles are contained.

(D) The master pellet of the above (c) is used as it is.

(Surface treatment of calcium carbonate particles)

The calcium carbonate particles in the present invention are preferably subjected to surface treatment with a surface treatment agent. Thereby, the Ca activity on the surface of the calcium carbonate particles is deactivated, so that the Ca activity of the surface can be turned into calcium carbonate particles, and the generation of the gas mark can be further suppressed. Examples of such a surface treatment agent include phosphorus compounds such as phosphoric acid, phosphorous acid, phosphonic acid, and derivatives thereof, fatty acids such as stearic acid, and silane coupling agents. In the present invention, surface treatment with a phosphorus compound is preferable among them. Specific examples of the phosphorus compound include phosphoric acid, phosphorous acid, trimethyl phosphate, tributyl phosphate, triphenyl phosphate, mono or dimethyl phosphate, Phosphorous acid trimethyl ester, methylphosphonic acid, methylsulfonic acid diethyl ester, phenylphosphonic acid dimethyl ester, and phenylphosphonic acid diethyl ester. Of these, phosphoric acid, phosphorous acid and ester-formed derivatives thereof are preferable. In the present invention, the surface treated with trimethyl phosphate is most preferable. These phosphorus compounds may be used singly or two or more of them may be used in combination.

The surface treatment method of the calcium carbonate particles is not particularly limited, and conventionally known methods can be employed. For example, when the surface treatment is carried out with a phosphorus compound, it is preferable to adopt a method (physical mixing method) of physically mixing the phosphorus compound and the calcium carbonate particles. Such a physical mixing method is not particularly limited, and a method of surface-treating a calcium carbonate with a phosphorus compound while pulverizing the calcium carbonate using various pulverizers such as a roll electric mill, a high-speed rotary mill, a ball mill and a jet mill, A container rotation type mixer in which the container itself rotates, a surface finishing method using a container fixed mixer having a rotating blade in a fixed container or blowing an air flow, and the like. Specifically, mixers such as a Nauter mixer, a ribbon mixer, and a Henschel mixer are preferable.

The treatment conditions at that time are not particularly limited. The treatment temperature is preferably 30 ° C or higher from the viewpoints of dispersibility of the calcium carbonate particles in the polyester, generation of foreign matter at the time of high temperature retention of the polyester, and foaming, Is preferably 50 占 폚 or higher, particularly 90 占 폚 or higher. The treatment time is preferably within 5 hours, more preferably within 3 hours, particularly within 2 hours. The phosphorus compound may be mixed with the calcium carbonate particles at the same time, or the phosphorus compound may be added after the calcium carbonate particles are injected in advance. At this time, the phosphorus compound may be dropped, sprayed, or dissolved or dispersed in water, alcohol, or the like.

In the present invention, the surface treatment agent of calcium carbonate particles may be added to and mixed with the polyester, and then the calcium carbonate particles may be added thereto to carry out the surface treatment of the calcium carbonate. For example, the surface treatment agent may be added at any stage from the production of the polyester, that is, until the completion of the polymerization reaction, or from the completion of the polymerization reaction to the time of performing the melt kneading.

The addition amount of the surface treatment agent in the surface treatment step may be such an amount that Ca activity on the surface of the calcium carbonate particles is sufficiently deactivated. For example, the amount of the phosphorus element in the amount of 0.1 mass% or more with respect to the mass of the calcium carbonate particle to be. On the other hand, if it is added too much, phosphorus compounds remain in the film in a large amount, which is not preferable from the viewpoint of the environment, and from the viewpoint of suppressing coagulation of the calcium carbonate particles in the extruder or the like, More preferably 2 mass% or less, further preferably 1 mass% or less, and particularly preferably 0.5 mass% or less.

(Emergency resin)

In the aspect b of the present invention, the reflective layer A contains an emissive resin as a void-forming agent.

Such an emergency resin is not particularly limited as long as it is non-reactive with the thermoplastic resin A constituting the reflective layer A. For example, in the case where the thermoplastic resin A is a polyester, it may be a polyolefin resin such as polyethylene, polypropylene, and polymethylpentene, a cycloolefin resin, a polystyrene resin, a polyacrylate resin, a polycarbonate resin, a polyacrylonitrile resin, Phenylene sulfide resin, fluorine resin, and the like are preferable. These may be used alone or in combination of two or more. It may be a homopolymer or a copolymer. In particular, it is preferable that the critical surface tension difference between the thermoplastic resin A and the thermoplastic resin A is preferably polyester. A resin which is hardly deformed by heat treatment after stretching is preferable. Specifically, a polyolefin-based resin is preferable. Examples of the polyolefin-based resin include polyolefin resins such as polyethylene, polypropylene and polymethylpentene, and copolymers thereof. Of these, a copolymer of ethylene and bicycloalkene, which is a cycloolefin copolymer, is particularly preferable.

The glass transition temperature of the nonconductive resin is preferably 180 占 폚 or higher and 220 占 폚 or lower, more preferably 190 占 폚 or higher and 220 占 폚 or lower. In the region where the glass transition temperature is lower than 180 占 폚, the voids developed at the time of stretching are deformed in the heat treatment step in the film production process, causing unevenness in void size and tendency to form coarse voids, The effect of improving the thermal bending tends to be lowered. Further, in the region higher than 220 deg. C, when the resin is melt-kneaded with the thermoplastic resin A constituting the reflective layer A, the non-resin is not sufficiently melted and the fine oxidation tends to be less likely to be promoted. There is a tendency to lose. As a method for controlling the glass transition temperature of the nonreciprocal resin, for example, an olefin moiety of a linear chain, such an olefin moiety is, for example, an ethylene moiety, and a cycloolefin moiety, and examples of such cycloolefin moiety include methylene- And the content of the cycloolefin moiety can be arbitrarily changed. For example, in order to increase the glass transition temperature, the copolymerization ratio of the cycloolefin moiety can be increased.

Examples of the non-resisting resin preferably used include TOPAS (registered trademark) COC series of Polyplastics Co., for example, Grade 6017S-04.

(Content of calcium carbonate particles in the aspect a)

In the aspect a, the reflective layer A is made of the thermoplastic resin composition A1 containing calcium carbonate particles. The content of the calcium carbonate particles in the thermoplastic resin composition A1 is preferably 10 mass% or more, Or more and 70 mass% or less. As a result, the above-mentioned desirable void volume ratio can be easily obtained, and thereby a high reflectance can be obtained. Also, thermal bending is suppressed. Further, the effect of improving the stretch film-forming property can be enhanced. If the content is too low, the reflectance is lowered. On the other hand, if the content is too large, the voids become too large, and thermal bending can not be suppressed. From these viewpoints, the content is preferably not less than 15% by mass, more preferably not less than 20% by mass, further preferably not more than 60% by mass, more preferably not more than 50% by mass.

(The content of the calcium carbonate particles and the nonconstituent resin in the aspect b)

In the aspect b, the content of the calcium carbonate particles in the thermoplastic resin composition A2 constituting the reflection layer A is 5 mass% or more and 69 mass% or less based on the mass of the thermoplastic resin composition A2. As a result, the above-mentioned desirable void volume ratio can be easily obtained, and thereby a high reflectance can be obtained. Also, thermal bending is suppressed. Further, the effect of improving the stretch film-forming property can be enhanced. If the content is too low, the reflectance is lowered. On the other hand, if the content is too large, the voids become too large, and thermal bending can not be suppressed. From these viewpoints, the content is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 60% by mass or less, and more preferably 50% by mass or less.

In embodiment (b), the content of the emulsion resin in the thermoplastic resin composition A2 constituting the reflective layer A is 1% by mass or more and 40% by mass or less based on the mass of the thermoplastic resin composition A2. As a result, the above-described desirable void volume ratio can be easily obtained while suppressing thermal warpage, thereby achieving a high reflectance. Further, the effect of improving the stretch film-forming property can be enhanced. If the content is too low, the reflectance is lowered. On the other hand, if the content is too large, the voids become too large, and thermal bending can not be suppressed. Further, a large amount of an emergency resin having a relatively low heat resistance is present in the film, and the thermal bending tends to be difficult to be suppressed thereby. From these viewpoints, the content is preferably not less than 5% by mass, more preferably not less than 10% by mass, further preferably not more than 35% by mass, more preferably not more than 30% by mass.

In the aspect b, the total content of the calcium carbonate particles and the non-permanent resin in the thermoplastic resin composition A2 constituting the reflective layer A is 10% by mass or more and 70% by mass or less based on the mass of the thermoplastic resin composition A2. As a result, the above-described preferable void volume ratio can be easily obtained while suppressing thermal warpage, and thereby a high reflectance can be obtained. Further, the effect of improving the stretch film-forming property can be enhanced. If the total content is too low, the reflectance is lowered. On the other hand, if the total content rate is too large, the thermal bending can not be suppressed for the same reason as in the case where the content of the above-mentioned calcium carbonate particles is too large or the content of the nonconductive resin is too large. From these viewpoints, the content is preferably at least 15 mass%, more preferably at least 20 mass%, further preferably at most 65 mass%, more preferably at most 60 mass%.

(Other components)

The reflective layer A, that is, the thermoplastic resin composition A constituting the reflective layer A, may contain other components such as an ultraviolet absorber, an antioxidant, an antistatic agent, Bleaching agent, and wax. In addition, as long as the object of the present invention is not impaired, a void-forming agent such as particles or resins different from the above-mentioned calcium carbonate particles or an emergency resin may be contained.

[Support layer B]

The white reflecting film of the present invention may have a supporting layer B composed of the thermoplastic resin composition B obtained by adding particles to the thermoplastic resin B or the thermoplastic resin B in addition to the above- By this support layer B, it is possible to improve the stretch film forming property or to further suppress the thermal warpage. Preferably, the support layer B having a smaller void than the reflective layer A or a composition having a heat-resistant as high as possible is formed on at least one surface of the reflective layer A, whereby local deformation due to heat can be further suppressed, Can be further suppressed.

Hereinafter, the support layer B in the present invention will be described in detail.

(Thermoplastic resin B)

As the thermoplastic resin B constituting the support layer B in the present invention, the same thermoplastic resin as the thermoplastic resin A constituting the aforementioned reflective layer A can be used. Among them, polyester is preferable from the viewpoint of obtaining a white reflective film excellent in mechanical properties and thermal stability.

As such a polyester, the same polyester as the polyester in the above-described reflective layer A can be used. Of these polyesters, aromatic polyesters are preferable, and polyethylene terephthalate is particularly preferable from the viewpoint of obtaining a white reflecting film excellent in mechanical properties and thermal stability. The polyester and preferably polyethylene terephthalate may be a homopolymer. However, since the crystallization is inhibited when the film is uniaxially or biaxially stretched and the effect of improving the film forming property of the film is enhanced, the copolymerized polyester and, furthermore, the copolymerized polyethylene terephthalate desirable. Examples of such a copolymerization component include the above-mentioned dicarboxylic acid component and diol component in the term of the reflective layer A, but from the viewpoint of high heat resistance and high effect of improving the stretch film forming property, the isophthalic acid component, 2,6-naphthalenedicarboxylic acid A carboxylic acid component is preferred. The content of the copolymerization component is, for example, not less than 1 mol%, preferably not less than 2 mol%, more preferably not less than 3 mol%, particularly preferably not less than 2 mol%, based on 100 mol% of the entire dicarboxylic acid component of the polyester , For example, 20 mol% or less, preferably 18 mol% or less, more preferably 17 mol% or less, and particularly preferably 16 mol% or less. When the ratio of the copolymerization component is within this range, the effect of improving the film forming property of the film is excellent. In addition, the thermal dimensional stability is excellent. Further, the effect of suppressing thermal bending can be further improved.

The melting point of the thermoplastic resin B is preferably 190 占 폚 or higher and 280 占 폚 or lower. This makes it easier to suppress the thermal bending. If it is too low, the effect of suppressing the thermal bending tends to be lowered, and if it is too high, the handling tends to be difficult. From this viewpoint, it is more preferably 195 DEG C or higher, more preferably 200 DEG C or higher, still more preferably 275 DEG C or lower, still more preferably 270 DEG C or lower.

The thermoplastic resin B constituting the support layer B in the present invention may be a mixture of a polyester as a preferable thermoplastic resin and another thermoplastic resin different from the polyester.

(Other components)

The support layer B may be made of the thermoplastic resin composition B containing any component within the range not hindering the object of the present invention. Examples of such optional components include an ultraviolet absorber, an antioxidant, an antistatic agent, a fluorescent whitening agent, and a wax.

In addition, the support layer B may contain a void-forming agent exemplified in the reflection layer A as an optional component in a range not hindering the object of the present invention, and by such an embodiment, the effect of improving the reflectance can be enhanced. On the other hand, if the content of the void-forming agent in the support layer B is reduced or the void-forming agent is not contained, the effect of improving the stretch film-forming property can be enhanced. From these viewpoints, the void volume ratio in the support layer B, the void volume ratio thereof is the ratio of the void volume in the support layer B to the volume of the support layer B, is preferably not less than 0% by volume and less than 15% by volume , More preferably not more than 5 vol%, particularly preferably not more than 3 vol%. Particularly, in the present invention, since it is possible to increase both the reflection property and the effect of improving the stretch film forming property, the preferable void volume ratio in the above-described reflection layer A and the preferable void volume ratio in such support layer B Is particularly preferable.

[Surface layer C]

The white reflecting film of the present invention may have a surface layer C composed of a thermoplastic resin composition C containing surface layer particles on at least one surface of the film. This surface layer C can impart a diffusing property to the reflected light, secure a gap with the light guide plate when contacting the light guide plate, or suppress the damage of the light guide plate. In order to exhibit such an effect, the surface layer C becomes the reflecting surface side in the film, and becomes the light source side or the light guide plate side in the backlight unit. In order to exhibit such effects, the average particle diameter of the surface layer particles is 2.0 占 퐉 or more and 50.0 占 퐉 or less, and the content thereof is 3% by volume or more and 50% by volume or less based on the volume of the thermoplastic resin composition C.

In order to achieve the above effect, it is preferable that the surface layer particles C have projections formed by the surface layer particles on the surface opposite to the reflective layer A as the surface of the surface layer C, , Preferably not more than 6.0 탆, and more preferably not less than 3.0 탆 and not more than 40.0 탆 in 10-point average roughness Rz. It is preferable that both Ra and Rz are within this range.

Hereinafter, the surface layer C in the present invention will be described in detail.

(Thermoplastic resin C)

As the thermoplastic resin C constituting the surface layer C in the present invention, the same thermoplastic resin as the thermoplastic resin A constituting the above-described reflective layer A can be used. Among them, polyester is preferable from the viewpoint of obtaining a white reflective film excellent in mechanical properties and thermal stability.

As such a polyester, the same polyester as the polyester in the above-described reflective layer A can be used. Of these polyesters, aromatic polyesters are preferable, and polyethylene terephthalate is particularly preferable from the viewpoint of obtaining a white reflecting film excellent in mechanical properties and thermal stability. The polyester and preferably polyethylene terephthalate may be a homopolymer. However, since the crystallization is inhibited when the film is uniaxially or biaxially stretched and the effect of improving the film forming property of the film is enhanced, the copolymerized polyester and, furthermore, the copolymerized polyethylene terephthalate desirable. Examples of such a copolymerization component include the above-mentioned dicarboxylic acid component and diol component in the term of the reflective layer A, but from the viewpoint of high heat resistance and high effect of improving the stretch film forming property, the isophthalic acid component, 2,6-naphthalenedicarboxylic acid A carboxylic acid component is preferred. The content of the copolymerization component is, for example, not less than 1 mol%, preferably not less than 2 mol%, more preferably not less than 3 mol%, particularly preferably not less than 2 mol%, based on 100 mol% of the entire dicarboxylic acid component of the polyester Is not less than 12 mol% and is, for example, not more than 20 mol%, preferably not more than 18 mol%, more preferably not more than 17 mol%, particularly preferably not more than 16 mol%. When the ratio of the copolymerization component is within this range, the effect of improving the film forming property of the film is excellent. In addition, the thermal dimensional stability is excellent. Further, the effect of suppressing thermal bending can be further improved.

The melting point of such a thermoplastic resin C is preferably 225 占 폚 or higher and 260 占 폚 or lower. This makes it easier to suppress the thermal bending. If it is too low, the effect of suppressing thermal bending tends to be lowered, while if it is too high, the handling tends to be difficult. From this viewpoint, it is more preferably 230 deg. C or higher, more preferably 235 deg. C or higher, still more preferably 258 deg. C or lower, still more preferably 256 deg.

The thermoplastic resin C constituting the surface layer C in the present invention may be a mixture of a polyester as a preferable thermoplastic resin and another thermoplastic resin different from the polyester.

(Surface layer particle)

In the present invention, by having the surface layer C, the diffusing property can be imparted to the reflected light. In addition, when the light guide plate is used in contact with the light guide plate, it is possible to secure a gap with the light guide plate and suppress damage to the light guide plate.

First, a description will be given of a preferred aspect of the surface layer particle when diffusing property is imparted to the reflected light. This embodiment is preferable for a direct-type backlight unit having a light source having a lens cap, and preferably an LED light source, particularly for a direct-type backlight unit.

In this case, in order to exert the above effect more effectively, the outer surface of the surface layer C preferably has Ra of at least 0.1 mu m, more preferably at least 0.2 mu m, further preferably at most 3.0 mu m, Is not more than 2.7 탆. Rz is preferably not less than 3.0 mu m, more preferably not less than 4.0 mu m, further preferably not more than 15.0 mu m, more preferably not more than 13.0 mu m. Such an aspect of the surface can be achieved by suitably adjusting with reference to the average particle diameter or the content of the surface layer particle to be described later.

As the surface layer particles used for the surface layer C at this time, it is preferable that the average particle size is 2.0 占 퐉 or more and 40.0 占 퐉 or less. In this manner, the diffusibility of the reflected light is easily improved. If the average particle diameter is too small, protrusions tend to be hardly formed, and the diffusibility of reflected light tends to be small. From this point of view, the average particle diameter of the surface layer particles is more preferably not less than 2.5 占 퐉, more preferably not less than 3.0 占 퐉, still more preferably not less than 3.5 占 퐉, particularly preferably not less than 4.0 占 퐉. On the other hand, if the surface layer particle used is too large, the filter or the like tends to be occluded when producing the film, and the surface layer particle tends to fall off from the surface layer C. From this viewpoint, it is more preferably 35.0 占 퐉 or less, still more preferably 30.0 占 퐉 or less, still more preferably 25.0 占 퐉 or less, particularly preferably 20.0 占 퐉 or less.

The content of the surface layer C in the surface layer C may be the surface layer C, that is, the thermoplastic resin composition C constituting the surface layer C, in order to make the aforementioned function of the surface layer C more easily exerted. , Preferably not less than 3% by volume and not more than 50% by volume. When the content is too small, the diffusibility of reflected light tends to be small. On the other hand, if it is too large, the filter tends to be clogged, and the surface layer particles tend to fall off easily. From this viewpoint, the content is more preferably 5% by volume or more, still more preferably 6% by volume or more, particularly preferably 10% by volume or more, still more preferably 45% by volume or less, 40 vol% or less, more preferably 35 vol% or less, particularly preferably 30 vol% or less.

In the present invention, the surface layer particles used for the surface layer C may be organic particles, inorganic particles, or organic-inorganic composite particles regardless of the kind thereof. More specifically, particularly preferred embodiments will be described. Preferred examples of the organic particles include fluorine-containing resin particles such as polytetrafluoroethylene, high heat-resistant nylon particles, and high heat-resistant acrylic particles. Preferred examples of the inorganic particles include titanium oxide particles, barium sulfate, calcium carbonate, zinc oxide particles, zirconium oxide particles, aluminum oxide particles, silica particles and the like.

Among them, agglomerated particles are preferable, and agglomerated inorganic particles are more preferable, and particularly, agglomerated silica particles are preferable. By employing such preferable surface layer particles, more preferable diffusion property can be obtained. This is because, in the present invention, it is preferable to use the aggregated particles as the surface layer particles of the surface layer C because diffusion of the light is desired in the aggregated particles, and the diffusibility of the reflected light can be further improved. The use of the agglomerated particles also has the effect of further suppressing the fracture failure at the time of stretching the film or suppressing the fracture failure and the optical characteristic at the time of producing the film by using the magnetic recovery raw material.

Further, the above-mentioned inorganic particles, high heat-resistant nylon particles and high heat-resistant acrylic particles also have an effect of being hardly melted or generating gas even when heated. It is also preferable in that it is difficult for the particle size distribution and the shape to change at the time of forming the surface layer C.

Next, preferred aspects of the surface layer particle in the case of providing a function of securing a gap with the light guide plate and suppressing the damage of the light guide plate will be described. This embodiment is particularly preferable for an edge light type backlight unit including a light guide plate.

In this case, in order to exert the above effect, the outer surface of the surface layer C preferably has Ra of 1.0 m or more, more preferably 1.5 m or more, and further preferably 6.0 m or less, Lt; / RTI > or less. Rz is preferably 6.0 mu m or more, more preferably 6.5 mu m or more, further preferably 40.0 mu m or less, and more preferably 35.0 mu m or less. Such an aspect of the surface can be achieved by suitably adjusting with reference to the average particle diameter or the content of the surface layer particle to be described later.

As the surface layer particles used for the surface layer C at this time, it is preferable that the average particle diameter is 3.0 mu m or more and 50.0 mu m or less. With such an embodiment, it is easy to secure a gap with the light guide plate and to suppress damage to the light guide plate. If the average particle diameter is too small, protrusions tend to be hardly formed, and there is a tendency that a gap with the light guide plate becomes difficult to secure. In addition, there is a tendency that a scratch easily occurs on the light guide plate. From this viewpoint, the average particle diameter of the surface layer particles is more preferably not less than 3.5 占 퐉, more preferably not less than 4.0 占 퐉, still more preferably not less than 4.5 占 퐉, and particularly preferably not less than 5.0 占 퐉. On the other hand, if the surface layer particles used are too large, the filter tends to be occluded when the film is produced, and the surface layer particles tend to fall off and the light guide plate tends to be damaged thereby. From this viewpoint, it is more preferably 48.0 占 퐉 or less, still more preferably 46.0 占 퐉 or less, still more preferably 44.0 占 퐉 or less, particularly preferably 42.0 占 퐉 or less.

The content of the surface layer particles in the surface layer C may be the surface layer C, that is, the thermoplastic resin composition C constituting the surface layer C, in order to more easily satisfy the aspect of the surface on the surface layer C It is preferably not less than 3% by volume and not more than 50% by volume based on the volume. If the content is too small, it tends to be difficult to secure a gap with the light guide plate and to suppress damage to the light guide plate. On the other hand, if it is too large, the filter tends to be clogged, and the surface layer particles tend to fall off easily. From this viewpoint, the content is more preferably 5% by volume or more, still more preferably 6% by volume or more, particularly preferably 10% by volume or more, still more preferably 45% by volume or less, 40 vol% or less, more preferably 35 vol% or less, particularly preferably 30 vol% or less.

In the present invention, the surface layer particles used for the surface layer C may be organic particles, inorganic particles, or organic-inorganic composite particles regardless of the kind thereof. More specifically, particularly preferred embodiments will be described. Preferred examples of the organic particles include fluorine-containing resin particles such as polytetrafluoroethylene, high heat-resistant nylon particles, and high heat-resistant acrylic particles. As preferable inorganic particles, aggregated inorganic particles are preferable. Examples of the agglomerated inorganic particles include agglomerated titanium oxide particles, agglomerated barium sulfate particles, agglomerated calcium carbonate particles, agglomerated zinc oxide particles, agglomerated zirconium particles, agglomerated aluminum oxide particles, and agglomerated silica particles. Among them, aggregated silica particles are preferable.

By employing such preferable surface layer particles, the effect of securing the gap with the light guide plate and suppressing the damage of the light guide plate is more excellent. This is considered to be because, in the present invention, by using agglomerated particles as the inorganic particles, it is preferable that the surface layer particles become moderately flexible, and that the effect of suppressing damage to the light guide plate can be further improved while securing a gap with the light guide plate. The use of the agglomerated particles also has the effect of further suppressing the fracture failure at the time of stretching the film or suppressing the fracture failure and the optical characteristic at the time of producing the film by using the magnetic recovery raw material.

Further, the above-mentioned inorganic particles, high heat-resistant nylon particles and high heat-resistant acrylic particles also have an effect of being hardly melted or generating gas even when heated. It is also preferable in that it is difficult for the particle size distribution and the shape to change at the time of forming the surface layer C.

(Other components)

The surface layer C may be made of the thermoplastic resin composition C containing any component in the range not hindering the object of the present invention. Examples of such optional components include an ultraviolet absorber, an antioxidant, an antistatic agent, a fluorescent whitening agent, and a wax.

The surface layer C may contain, as an optional component, the void-forming agent exemplified in the reflective layer A within the range not hindering the object of the present invention, and by such an embodiment, the effect of improving the reflectance can be enhanced. On the other hand, if the content of the void-forming agent in the surface layer C is reduced or the void-forming agent is not contained, the effect of improving the film-forming property can be enhanced. From these viewpoints, the void volume ratio in the surface layer C, and the void volume ratio thereof are the ratio of the volume of the voids in the surface layer C to the volume of the surface layer C, is preferably 0 volume% or more and less than 15 volume% By volume, more preferably not more than 5% by volume, particularly preferably not more than 3% by volume. Particularly, in the present invention, the preferable void volume ratio in the above-described reflective layer A and the preferable void volume ratio in the surface layer C are simultaneously adopted because the reflection property and the effect of improving the stretch film- Is particularly preferable.

[Floor composition]

In the present invention, the thickness of the white reflecting film is preferably 155 占 퐉 or more and 350 占 퐉 or less. Here, this thickness is the thickness of the reflective layer A when only the reflective layer A is made of the white reflective film. As a result, the effect of improving the reflectance can be enhanced. In addition, the effect of improving thermal bending can be enhanced. If it is too thin, the effect of improving the reflectivity is low, and the effect of improving the thermal bending inhibition is low, and if it is too thick, it is inefficient. From this viewpoint, it is more preferably not less than 160 mu m, more preferably not less than 170 mu m, particularly preferably not less than 180 mu m, more preferably not more than 340 mu m, further preferably not more than 330 mu m, Or less.

The reflective layer A should have a thickness ratio of preferably 50% or more, more preferably 60% or more, more preferably 70% or more, with the thickness of the entire white reflective film being 100% , Preferably not more than 95%, more preferably not more than 90%. Here, the thickness ratio is a ratio of the total thickness when a plurality of the reflection layers A are provided. When the support layer B is provided, the thickness ratio thereof is preferably 5% or more, more preferably 10% or more, further preferably 50% or less, more preferably 40% or less, 30% or less. Here, the thickness ratio is a ratio of the total thickness when a plurality of support layers B are provided. This makes it possible to improve the balance of the respective characteristics such as the reflection characteristic and the stretch film forming property. In addition, it is possible to make the balance better, and to further improve the effect of suppressing thermal bending.

The thickness of the support layer B in the present invention is preferably 2 mu m or more and 80 mu m or less. Here, this thickness is the total thickness when a plurality of supporting layers B are present in the film. Thereby, the effect of improving the stretch film-forming property can be enhanced, and the effect of suppressing thermal bending can be enhanced. Also, the heat shrinkage can be reduced. If the support layer B is too thin, the effect of improving the stretch film-forming property tends to be lowered. Further, the effect of suppressing thermal bending tends to be lowered. On the other hand, if it is too thick, the effect does not change so much and is inefficient. From these viewpoints, the thickness (total thickness) of the support layer B is more preferably 5 占 퐉 or more, further preferably 10 占 퐉 or more, further preferably 70 占 퐉 or less, further preferably 65 占 퐉 or less.

When the supporting layer B is provided on the reflective surface side of the reflective layer A, the thickness of the supporting layer B affects the reflectance. That is, when the thickness of the supporting layer B on the reflective surface side of the reflective layer A is too thick, the effect of improving the reflectivity tends to be lowered. On the other hand, if it is too thin, the effect of suppressing the dropping of the calcium carbonate particles of the reflection layer A and the effect of suppressing the damage of the apparatus and other members due to the calcium carbonate of the reflection layer A tend to be lowered. From these viewpoints, the thickness of the support layer B is preferably not less than 1 占 퐉 and not more than 40 占 퐉, more preferably not less than 2.5 占 퐉, more preferably not less than 5 占 퐉, more preferably not more than 35 占 퐉 Preferably 32.5 占 퐉 or less. Here, this thickness is the thickness of one layer of the support layer B.

When the white reflective film has the reflective layer A and the supporting layer B, when the reflective layer A and the supporting layer B are represented by A and B, the two-layer structure of A / B / A and B / A / B, a four-layer structure of B / A / B / A or B / A / B '/ A and a multilayer structure of five or more layers of A and B in the same manner. In the above, B 'represents a support layer B' having the same structure as the support layer B and having a different structure. Particularly preferred is a two-layer structure of B / A, and a three-layer structure of A / B / A and B / A / B. Most preferably B / A / B, and is superior in stretch film formability. Further, if the support layer B of the front and back surfaces is in a range of a near-thickness range, problems such as curls are unlikely to occur.

In the present invention, in addition to the reflective layer A and the supporting layer B, other layers may be provided as long as the object of the present invention is not impaired. For example, it may have a layer for imparting functions such as antistatic property, conductivity, ultraviolet durability and the like. This layer is preferably a coating layer. Further, the bead layer containing beads for securing the diffusing property to the reflected light or securing the gap with the light guide plate may be provided on the uppermost surface of at least one surface on the reflection surface side. The surface layer C is a preferred embodiment of the bead layer.

In the case of having the surface layer C, the thickness of the surface layer C in the present invention is preferably 5 mu m or more and 70 mu m or less. Here, this thickness is a thickness of one layer which is on the light source side or the light guide plate side when the film has a plurality of surface layers C therein. As a result, the above-described effect of the surface layer C can be more easily exerted. If it is too thin, the surface layer particles tend to fall off. On the other hand, if it is too thick, it tends to be difficult to form a projection, and the above-mentioned effect tends to be hardly exerted. It is also economically inefficient. From this viewpoint, it is more preferably 10 m or more and 60 m or less.

When the white reflective film has the reflective layer A and the surface layer C, the laminated structure thereof is a two-layer structure of C / A, a three-layer structure of C / A / C, A four-layer structure of C / A / C / A or C / A / C '/ A and a multilayer structure of five or more layers of A and C. In the above, C not present on the surface indicates the inner layer C having the same constitution as the surface layer C. C 'represents a surface layer C' having the same constitution as the surface layer C and having a different constitution. Particularly preferred is a two-layer structure of C / A and a three-layer structure of C / A / C. Most preferably C / A / C, and is superior in stretch film formability. In addition, if the surface layer C of the front and back surfaces is in the range of a near thickness, problems such as curl are unlikely to occur.

When the white reflecting film has the reflective layer A, the supporting layer B and the surface layer C, the layered structure is a three-layer structure of C / B / A or C / A / B, Layer structure of A / B / A or C / B / A / B and a five-layer structure of C / B / A / B / A or C / B / A / B ' And a surface layer C on the surface of at least a single-layered multi-layered structure having six or more layers. In the above, B 'represents a support layer B' having the same structure as the support layer B and having a different structure. Particularly preferred is a three-layer structure of C / B / A and C / A / B, and a four-layer structure of C / A / B / A and C / B / A / Most preferably a four-layer structure of C / B / A / B, and is superior in stretch film formability. Further, if the support layer B of the front and back surfaces is in a range of a near-thickness range, problems such as curls are unlikely to occur.

[Production method of film]

Hereinafter, an example of a method for producing the white reflecting film of the present invention will be described.

In producing the white reflecting film of the present invention, the reflective layer A is preferably formed by melt extrusion. In the case where the white reflective film has a laminated structure of the reflective layer A and the supporting layer B, or the laminated structure of the reflective layer A and the surface layer C, or the laminated structure of the reflective layer A, the supporting layer B and the surface layer C, It is preferable that they are laminated by the extrusion method. As a result, the effect of improving the stretch film-forming property can be enhanced. It is preferable that the reflection layer A and the support layer B, or the reflection layer A and the surface layer C, or the reflection layer A, the support layer B and the surface layer C are directly laminated by a co-extrusion method. By laminating them by the co-extrusion method as described above, it is possible to increase the interfacial adhesion of each layer, and it is necessary to carry out a process for bonding the film or forming the support layer B or the surface layer C again after film formation It can be mass-produced inexpensively and easily.

Hereinafter, an example of a more specific production method of the white reflective film of the present invention will be described, but the present invention is not limited to such a production method, and other aspects can be similarly manufactured with reference to the following. At that time, when the extrusion step is not included, the following "melt extrusion temperature" can be read by, for example, "melt temperature". Here, the melting point of the polyester to be used is Tm (unit: 占 폚) and the glass transition temperature is Tg (unit: 占 폚).

When polyester is used as the thermoplastic resin A constituting the reflection layer A and the thermoplastic resin B constituting the support layer B and the coextrusion method is adopted as the lamination method, , Which is also referred to as a polyester composition A when polyester is used as the thermoplastic resin A, and in the case of containing the polyester and the calcium carbonate particles and the nonreinforced resin, the thermoplastic resin composition A for forming the cycloolefin And other optional components are prepared. Further, a thermoplastic resin composition B for forming the support layer B, which is also referred to as a polyester composition B when polyester is used as the thermoplastic resin B, is prepared by mixing a polyester and other arbitrary components. Here, as the support layer B, thermoplastic resin B may be used without adding any other optional components, and polyester such as thermoplastic resin B may be used. These polyester compositions are used by drying and sufficiently removing moisture.

When polyester is used as the thermoplastic resin A constituting the reflective layer A and the thermoplastic resin C constituting the surface layer C and the coextrusion method is adopted as the case of having the reflective layer A and the surface layer C, A thermoplastic resin composition A for forming the reflective layer A, which is also referred to as polyester composition A when polyester is used as thermoplastic resin A, is prepared by mixing polyester, calcium carbonate particles, and other optional components . The thermoplastic resin composition C for forming the surface layer C is also referred to as a polyester composition C when polyester is employed as the thermoplastic resin C, which is a mixture of polyester, surface layer particles and other arbitrary components do. These polyester compositions are used by drying and sufficiently removing moisture.

Next, the dried polyester composition is put into different extruders and melt-extruded. The melt extrusion temperature needs to be not less than Tm and may be set to about Tm + 40 占 폚.

At this time, the polyester composition used in the production of the film, in particular, the polyester composition A used for the reflection layer A, is preferably a nonwoven fabric having a mean scale size of 10 탆 or more and 100 탆 or less and made of stainless steel fine wire having a line diameter of 15 탆 or less It is preferable to perform filtration using a filter. By carrying out this filtration, it is possible to suppress the agglomeration of the particles, which are usually aggregated and tend to become coarse aggregated particles, and to obtain a film having small coarse foreign matters. By suppressing the agglomerated particles, microvoids are easily formed, and thermal bending is further suppressed. The average scale size of the nonwoven fabric is preferably 15 占 퐉 or more, more preferably 20 占 퐉 or more, further preferably 50 占 퐉 or less, further preferably 40 占 퐉 or less. The thermoplastic resin composition C is preferably 35 占 퐉 or more, more preferably 40 占 퐉 or more, further preferably 70 占 퐉 or less, further preferably 60 占 퐉 or less. The filtered polyester composition is extruded from a die into a multi-layer state by simultaneous multilayer extrusion using a feed block in a molten state, that is, co-extrusion, to produce an unoriented laminated sheet. The unstretched laminated sheet extruded from the die is cooled and solidified by a casting drum to obtain an unstretched laminated film.

Then, the unstretched laminated film is heated by roll heating, infrared heating, or the like, and stretched in the film forming machine axial direction (hereinafter sometimes referred to as longitudinal direction or longitudinal direction or MD) to obtain a longitudinal stretched film. This stretching is preferably carried out using the main speed difference of two or more rolls. The film after the longitudinal stretching is continuously stretched in the tenter in the longitudinal direction and in the direction perpendicular to the thickness direction (hereinafter sometimes referred to as the transverse direction or the width direction, or TD) to obtain a biaxially stretched film .

The stretching temperature is preferably at least the Tg of the polyester, preferably at least the Tg of the polyester constituting the reflective layer A, and Tg + 30 deg. C or less, more preferably the stretched film formability, . The draw ratio is preferably 2.5 to 4.3 times, more preferably 2.7 to 4.2 times in both the longitudinal direction and the transverse direction. If the stretching ratio is too low, the film thickness tends to be uneven, and voids tend to be hardly formed. On the other hand, if it is too high, breakage tends to occur during film formation. It is preferable that the second stage, that is, the transverse stretching in this case, is higher by about 10 to 50 ° C than the first stage stretching temperature at the time of sequential biaxial stretching such as longitudinal stretching followed by longitudinal stretching Do. This is because the Tg of the uniaxial film is raised by being oriented by the first-stage stretching.

It is preferable to preheat the film before each stretching. For example, the preheating treatment for transverse stretching is a step of gradually increasing the temperature, starting from a temperature higher than Tg + 5 deg. C of polyester, which is preferably polyester constituting the reflective layer A. The temperature increase during the transverse stretching process may be continuous or stepwise (also referred to as recursive), but it usually raises the temperature incrementally. For example, the transverse stretching zone of the tenter is divided into a plurality of portions along the film running direction, and the temperature is raised by flowing a heating medium at a predetermined temperature for each zone.

The biaxially stretched film is successively subjected to heat fixation and heat relaxation treatment successively to form a biaxially oriented film, but these processes can be carried out while continuing to perform the stretching from the melt extrusion to the film.

The film after the biaxial stretching is subjected to a heat treatment for 0.01 to 100 seconds at a constant width or a width reduction of 10% or less at (Tm - 10 ° C) to (Tm - 100 ° C) with the melting point of polyester as Tm It is preferable that the heat shrinkage rate is lowered. The melting point is preferably the melting point of the polyester constituting the reflective layer A. If the heat treatment temperature is too high, the flatness of the film tends to deteriorate, and the thickness unevenness tends to become large. On the other hand, if it is too low, the heat shrinkage tends to increase. Further, the effect of suppressing thermal bending can be further improved.

Further, in order to adjust the amount of heat shrinkage, both ends of the gripped film can be cut out, and the pulling speed in the film longitudinal direction can be adjusted to relax in the longitudinal direction. As a means of relaxation, the speed of the roll group on the tenter output side is adjusted. As the rate of relaxation, the speed of the roll group is lowered with respect to the film line speed of the tenter, and the speed reduction is preferably 0.1 to 2.5%, more preferably 0.2 to 2.3%, particularly preferably 0.3 to 2.0% (Hereinafter, this value may be referred to as " relaxation ratio " in some cases), and the heat shrinkage rate in the longitudinal direction is adjusted by controlling the relaxation rate. Further, the effect of suppressing thermal bending can be further improved. With respect to the transverse direction of the film, the width is reduced in the process until both ends are cut out, and a desired heat shrinkage ratio can be obtained.

Further, in biaxial stretching, besides longitudinal-transverse biaxial stretching as described above, transverse-longitudinal biaxial stretching may also be employed. Also, the film can be formed by using the simultaneous biaxial stretching method. In the case of the simultaneous biaxial stretching method, the draw ratio is, for example, 2.7 to 4.3 times, preferably 2.8 to 4.2 times in both the longitudinal and transverse directions.

Thus, the white reflecting film of the present invention can be obtained.

[Characteristics of white reflective film]

(Reflectance, front luminance)

The reflectance of the white reflecting film of the present invention is 60% or more. , Preferably at least 70%, more preferably at least 80%, more preferably at least 90%, particularly preferably at least 95%, and most preferably at least 97%. When the reflectance is in the above-mentioned range, high luminance can be obtained when used in a liquid crystal display device or an illumination. Such a reflectance may be set to a preferable mode such as increasing the void volume ratio of the reflective layer A, or the thickness of the reflective layer A may be increased. In the case of having the supporting layer B or the surface layer C, The thickness of the support layer B or the surface layer C on the reflective surface side is made thinner than that of the reflective layer A, which is preferable.

The front luminance is determined by a measuring method to be described later, but is preferably 2000 cd / m 2 or more, more preferably 3,000 cd / m 2 or more, more preferably 4000 cd / m 2 or more, and more preferably 4400 cd / Particularly preferred.

Here, the reflectance and the front luminance are values for the surface to be used as the reflective surface of the white reflective film.

(Thermal bending)

The present invention aims at suppressing thermal bending. Thermal bending is a phenomenon in which heat is generated from an electric circuit for driving a display device such as a liquid crystal display or a backlight unit or a light source in a product such as a television or a monitor, A warpage or deformation occurs in the white reflecting film provided. When the white reflecting film is thermally warped, it causes luminance unevenness, which is directly related to the deterioration of image quality.

[Usage]

The white reflective film of the present invention is for a large display. Here, a large display means a liquid crystal display of 30 inches or more, preferably 32 inches or more, more preferably 40 inches or more, and more preferably 42 inches or more. In such a large-sized display, a depression or a partition for inserting an electric circuit or the like is formed in the back chassis. Therefore, heat generated due to the above-described causes locally stays in such depressed portions, and thermal bending is more likely to occur. As the size of the display increases, the number of light sources necessary for securing the brightness increases, so that the number of heat retention increases in view of the complexity of circuits and the like, and thermal bending tends to be more likely to occur. Therefore, it has been difficult to suppress the thermal bending in such a large-sized display by the conventional technique. On the contrary, the present invention can suppress thermal bending well even in such a large display.

Example

Hereinafter, the present invention will be described in detail by way of examples. Each property value was measured by the following method.

(1) Light reflectance

The reflectance was measured at a wavelength of 550 nm when an integrating sphere was attached to a spectrophotometer (UV-3101PC manufactured by Shimadzu Corporation) and the BaSO ₄ white plate was made 100%, and this value was used as the reflectance. The measurement was carried out on the side used as the reflection surface, that is, on the surface serving as the light source side.

(2) average particle diameter of the particles

Was measured using a laser scattering type particle size distribution measuring apparatus SALD-7000 manufactured by Shimadzu Corporation. The dispersion in ethylene glycol before measurement was measured so that the powder of the particles was equivalent to the concentration of 5 mass% slurry, stirred for 10 minutes by a mixer, cooled to room temperature, and then supplied to a flow cell type feeder. As a mixer, for example, a National MXV253 type cooking mixer is used. Then, ultrasonic treatment was performed for 30 seconds for defoaming from the supply device, and the measurement was provided for measurement. The intensity of the ultrasonic wave in the ultrasonic wave treatment was set at a position of 60% from the position showing the MAX value by the knob of the ultrasonic wave processing device. The 50% volume particle diameter (D50) was determined from the particle size distribution measurement results, and the average particle diameter was determined. In the same manner, 10% volume particle diameter (D10) and 90% volume particle diameter (D90) were determined.

(3) Content of particles and non-residual resin

(3-1) Content of particles

The film was incinerated at a temperature of 500 DEG C for 6 hours, the weight before and after the incineration was measured, and the weight of the residual ash was determined as the content of the particles. The content of the particles of each layer in the laminate was obtained by separating each layer and then carrying out the above-mentioned operation.

(3-2) Emulsion resin content

The film was weighed and then dissolved in a mixed solvent of hexafluoroisopropanol (HFIP) / chloroform in a mass ratio of 50/50. When the insoluble component was present, the insoluble component was collected by centrifugation, The structure and mass fraction of the components are measured by elemental analysis, FT-IR and NMR. By analyzing the same for the supernatant component, the mass fraction and the structure of the polyester component and the other component can be specified. After the solvent was distilled off from the supernatant, the solution was dissolved in a mixed solvent of HFIP / chloroform at a mass ratio of 50/50, and ¹ H-NMR spectrum was measured.

From the obtained spectrum, the peak area intensity of the absorption specific to each component is obtained, and the molar ratio of the blend from the ratio and the proton number is calculated. Further, the mass ratio is calculated from the food equivalent to the unit unit of the polymer. Thus, the mass fraction and the structure of each component are specified.

The content of the particles of each layer in the laminate was obtained by separating each layer and then carrying out the above-mentioned operation.

(4) Film thickness and layer composition

The white reflective film was sliced with a microtome and cross-sectioning was performed. The cross section was observed at a magnification of 500 times by using a S-4700 field emission scanning electron microscope manufactured by Hitachi, Ltd., and the entire film, the reflective layer A, And the thickness of the surface layer C were respectively determined. The thickness was measured as an average by measuring an arbitrary position with n = 7. The thickness (占 퐉) of each layer was determined and then the thickness ratio of each layer was calculated.

(5) Calculation of void volume ratio

The calculated density was obtained from the density and mixing ratio of the polymer, additive particles, and other components in the layer for obtaining the void volume ratio. At the same time, the layer was peeled off and separated, and the mass and volume were measured. From these, the actual density was calculated, and the physical density and the actual density were determined by the following formula.

Void volume ratio = 100 x (1 - (true density / calculated density))

The density of the isophthalic acid copolymerized polyethylene terephthalate after biaxially stretching was 1.39 g / cm 3, the density of the calcium carbonate particles was 2.7 g / cm 3, the density of the barium sulfate particles was 4.5 g / cm 3, and the density of the cycloolefin copolymer The density was 1.02 g / cm3.

In addition, only the layer for measuring the void volume ratio was isolated, and the mass per unit volume was determined to obtain the actual density. The volume was calculated by cutting the sample to an area of 3 cm 2 and measuring the thickness at that size by an electric micrometer (K-402B manufactured by Anritsu K-402B) at an average value of 10 times the area and the thickness. The mass was weighed by an electronic balance.

As the specific gravity of the other particles including the aggregated particles, the value of the bulk specific gravity determined by the following mass cylinder method was used. The weight of the entire cylinder was measured by measuring the weight of the entire cylinder, subtracting the weight of the cylinder from the total weight of the cylinder, measuring the volume of the cylinder, And dividing the weight (g) of the particle by the volume (cm 3) thereof.

(6) Melting point, glass transition temperature

Measurement was carried out at a heating rate of 20 占 폚 / min using a differential scanning calorimeter (TA Instruments 2100 DSC).

(7) Front luminance

(7-1) Front luminance 1

A reflective film was taken out from an edge light type LED liquid crystal television (LG42LE5310AKR) (42 inches) manufactured by LG Corporation, and instead the various reflective films obtained in the examples were set so that the reflective surface side was on the screen side, A diffusing film and a prism sheet were disposed, and the luminance was measured using a luminance meter (Model MC-940 manufactured by Otsuka Electronics) as the state of the backlight unit.

(7-2) Front luminance 2

A reflective film was taken out from a direct-lit LED light type liquid crystal television (LG LN5400) (42 inches) manufactured by LG Corporation, and instead, the various reflective films obtained in the examples were installed so that the reflective surface side was on the screen side, And the luminance was measured using a luminance meter (Model MC-940 manufactured by Otsuka Electronics Co., Ltd.) in the state of the backlight unit.

(8) Stretch film forming property

The film stability of the film described in the examples when the film was formed by the continuous film forming method using a tenter was observed and evaluated according to the following criteria.

◎: The film can be stably formed for 8 hours or more.

○: The film can be stably formed for 3 hours to less than 8 hours.

[Delta]: 1 cut occurred in less than 3 hours.

X: Cutting occurs more than once in less than 3 hours, and stable film formation can not be performed.

(9) Evaluation of thermal bending

(42 inches) of an edge light type LED liquid crystal television (LG42LE5310AKR) manufactured by LG Corporation was disassembled and a reflective film originally provided thereon was taken out. Instead, a white reflective film of the example was arranged, the television was assembled, The television was kept in an environment of 80% RH at a temperature of 50 캜 for 72 hours while being turned on in a white display, and the luminance unevenness before and after that was evaluated.

(9-1) Evaluation of luminance unevenness 1

The luminance unevenness was visually judged and evaluated according to the following criteria.

○: No luminance irregularity can be seen at all.

B: The brightness unevenness is barely recognized.

X: Significant luminance unevenness can be seen.

(9-2) Evaluation of luminance unevenness 2

The luminance per 10 arbitrary points on average was measured on the screen with a luminance meter (CA-2000 manufactured by Konica Minolta Co.), and the value of [(maximum luminance - minimum luminance) / average luminance] in the screen was evaluated. When the value described above is 5% or less, it can be determined that the state is in a good state because the brightness unevenness due to thermal bending is small. , Preferably not more than 4%, more preferably not more than 3%.

(10) Evaluation of Light Guide Plate

The chassis is taken out from an LED liquid crystal television (LG42LE5310AKR) manufactured by LG, placed on a horizontal table so that the inside of the TV is upward, and a reflective film almost the same size as the chassis is placed thereon so that the surface layer surface is upward On top of this, three light guide plates and optical sheets originally provided in the television set, two such optical sheet three diffuse films and one prism were placed. Subsequently, on the surface, an equilateral triangle having three circumferential legs each having a diameter of 5 mm is placed in an area including the portion where the concavities and convexities of the chassis are the most severe, as shown in Fig. 1, A weight of 15 kg was placed, and the area surrounded by these three legs was visually observed. When there was no abnormally bright part, "no adhesion non-uniformity" was evaluated. When there is an unsteadily bright part, a DBEF sheet originally provided on the television is placed on three optical sheets, and the same observation is made with naked eyes. If the unstable bright part is not recovered, Quot ;, that is, evaluation x, and when there is no abnormal bright portion, " almost no adhesion unevenness " In addition, the area surrounded by the three legs was approximately equilateral triangle having a length of 10 cm.

≪ Preparation Example 1: Synthesis of isophthalic acid copolymerized polyethylene terephthalate 1 >

136.5 parts by mass of dimethyl terephthalate and 13.5 parts by mass of dimethyl isophthalate, that is, the isophthalic acid component is 9 mol% based on 100% by mol of the total acid component of the obtained polyester. 98 parts by mass of ethylene glycol, 1.0 part by mass of diethylene glycol, 0.05 parts by mass of manganese and 0.012 parts by mass of lithium acetate were introduced into a flask equipped with a rectification tower and a distillation condenser and heated at 150 to 240 ° C with stirring to distill methanol to effect transesterification reaction. After methanol was spilled out, 0.03 parts by mass of trimethyl phosphate and 0.04 parts by mass of germanium dioxide were added, and the reaction product was transferred to the reactor. Subsequently, the inside of the reactor was gradually reduced to 0.3 mmHg while stirring, and the temperature was raised to 292 ° C to carry out a polycondensation reaction to obtain isophthalic acid copolymerized polyethylene terephthalate 1. The melting point of this polymer was 235 ° C.

≪ Preparation Example 2: Synthesis of isophthalic acid copolymerized polyethylene terephthalate 2 >

, 129.0 parts by mass of dimethyl terephthalate, 21.0 parts by mass of dimethyl isophthalate, that is, the isophthalic acid component was 14 mol% based on 100 mol% of all the acid components of the polyester to be obtained. , Isophthalic acid copolymerized polyethylene terephthalate 2 were obtained. The melting point of this polymer was 215 ° C.

≪ Preparation Example 3: Production of particle master chip 1 >

A part of the obtained isophthalic acid copolymerized polyethylene terephthalate 1 and a synthetic calcium carbonate particle having an average particle diameter of 0.9 mu m and (D90-D10) / D50 of 1.4 were used as a void-forming agent, and a NEX-T60 tandem extruder , The mixture was mixed so that the content of the synthetic calcium carbonate particles was 60% by mass with respect to the mass of the obtained master chip, and the mixture was extruded at a resin temperature of 260 캜 to prepare a particle master chip 1 containing synthetic calcium carbonate particles. These synthetic calcium carbonate particles are surface-treated with trimethyl phosphate.

≪ Preparation Example 4: Production of particle master chip 2 >

Synthesis of Particle Master Chip 2 Containing Synthetic Calcium Carbonate Particles The procedure of Production Example 3 was repeated except that the isophthalic acid copolymerized polyethylene terephthalate 2 obtained above was used in place of the isophthalic acid copolymerized polyethylene terephthalate 1.

≪ Preparation Example 5: Production of particle master chip 3 >

Particles obtained by subjecting the isophthalic acid copolymerized polyethylene terephthalate 2 obtained above to an average particle size of 6.5 mu m by wind force classification as AY-601 manufactured by Tosoh Silica Co., Ltd., which is a coagulated silica, as the particle A, The mixture was mixed with a twin-screw extruder so as to have a concentration of 8 mass% and extruded at a melting temperature of 250 캜 to prepare a particle master chip 3.

≪ Preparation Example 6: Preparation of Particle 1 to be used in the bead layer >

150 parts by mass of dimethyl terephthalate, 98 parts by mass of ethylene glycol, 1.0 part by mass of diethylene glycol, 0.05 part by mass of manganese acetate and 0.012 parts by mass of lithium acetate were fed into a flask equipped with a rectifying column and an outlet condenser, The methanol was distilled by heating to carry out an ester exchange reaction. After methanol was spilled out, 0.03 parts by mass of trimethyl phosphate and 0.04 parts by mass of germanium dioxide were added, and the reaction product was transferred to the reactor. Subsequently, the inside of the reactor was gradually reduced to 0.3 mmHg while stirring, and the temperature was raised to 292 ° C, and a polycondensation reaction was carried out to obtain polyethylene terephthalate 3. The obtained polyethylene terephthalate 3 was extruded from a strand die, cooled and cut to obtain a pellet shape. As a result of adjusting the shape of the strands, the shape of the pellets was almost rectangular parallelepiped, and the average shape was 4 mm x 3 mm x 2 mm. Then, the obtained pellets were dried and crystallized by heating at 170 ° C for 3 hours in an oven, and pulverized while cooling with liquid nitrogen using an atomizer mill TAP-1 manufactured by Matsubo Co., Ltd. to obtain a polyester having an average particle size of 60 μm Particles were obtained. The polyester particles were classified by wind force to obtain particles 1 having an average particle diameter of 43 탆, which were non-spherical particles.

[Example 1-1]

(Preparation of white reflective film)

The isophthalic acid copolymerized polyethylene terephthalate 1 and the particle master chip 1 obtained as described above were used as a material for the reflection layer (A layer), and the isophthalic acid copolymerized polyethylene terephthalate 2 and the particle master chip 2 were used as the support layer Each of the layers was mixed so as to have the composition described in Table 1, and the resulting mixture was introduced into an extruder. The A layer was passed through a nonwoven fabric filter having an average graduation size of 30 占 퐉, Was passed through a nonwoven fabric filter having an average graduation size of 30 占 퐉 and joined at a melt extrusion temperature of 230 占 폚 using a three-layer feed block device so as to have a layer structure of B layer / A layer / B layer as shown in Table 1, The sheet was formed into a sheet from the dies while maintaining the laminated state. At this time, the thickness ratio of the B layer / A layer / B layer was adjusted to be 10/80/10 after biaxial stretching by the discharge amount of each extruder. This sheet was further cooled and solidified with a cooling drum having a surface temperature of 25 DEG C to form an unstretched film. The unstretched film was passed through a preheating zone at 73 占 폚 and then a preheating zone at 75 占 폚 and was led to a longitudinal stretching zone maintained at 92 占 폚 and stretched 3.0 times in the longitudinal direction and cooled by a roll group of 25 占 폚. Subsequently, both ends of the film were passed through a preheating zone at 115 캜 while being held by a clip, and were led to a transverse stretching zone maintained at 130 캜 and stretched 3.6 times in the transverse direction. Thereafter, heat treatment at 155 占 폚 for 10 seconds, heat fixation at 200 占 폚 for 10 seconds, and heat treatment at 155 占 폚 for 10 seconds were successively performed in the tenter, and then, at a width filling ratio of 2% Then, both ends of the film were cut out, heat relaxed to 2.5% of paper percentage, and cooled to room temperature to obtain a film having a thickness of 300 탆. Table 1 shows the evaluation results of the obtained film.

[Examples 1-2 to 1-9, 1-11, Comparative Examples 1-1 to 1-6]

A white reflective film was obtained in the same manner as in Example 1-1 except that the mode of the particles and the structure of the film were changed as shown in Table 1. [ Table 1 shows the evaluation results of the obtained film. The synthetic calcium carbonate particles used were surface-treated with trimethyl phosphate.

In Example 1-11, the total thickness of the film was 188 탆.

[Comparative Example 1-7]

A particle master chip was produced in the same manner as in Production Examples 3 and 4 except that barium sulfate particles having an average particle diameter of 0.9 mu m and (D90 - D10) / D50 of 1.4 were used as the void forming agent in place of the calcium carbonate particles, Was prepared in the same manner as in Example 1-1, except that the composition of the white reflecting film was changed as shown in Table 1. Table 1 shows the evaluation results of the obtained film. These barium sulfate particles were obtained by repeating wind power classification.

[Example 1-10]

On one side of the biaxially oriented film obtained in the same manner as in Example 1-1, a coating liquid having the composition shown in Fig. 1 for forming the following bead layer was coated with a direct gravure coating apparatus in an application amount of a wet thickness of 15 g / , And then dried at 100 DEG C in an oven to obtain a white reflective film having a bead layer. Table 1 shows the evaluation results of the obtained film. In the evaluation, the side of the bead layer was used as the reflecting surface.

<Coating 1, solid concentration 30% by mass>

Particle: Particle 1 (non-spherical particle) obtained in Preparation Example 6 7.5 mass%

Acrylic resin (thermoplastic resin): Acridic A-817BA (solid concentration 50% by mass) manufactured by DIC Co., Ltd. 30 mass%

Crosslinking agent: Colonate HL (isocyanate crosslinking agent, solid concentration 75% by mass) manufactured by Nippon Polyurethane Industry Co., Ltd. 10 mass%

Diluent solvent: butyl acetate 52.5 mass%

The solid content ratio of each component in the coating solution 1 is as follows.

Particles: 25 mass%

Acrylic resin (thermoplastic resin): 50 mass%

Crosslinking agent: 25 mass%

[Example 2-1]

(Preparation of white reflective film)

The isophthalic acid copolymerized polyethylene terephthalate 1 obtained above, the particle master chip 1, and the nonreciprocal resin (cycloolefin copolymer, Tg = 210 캜, TOPAS manufactured by Polyplastics Co., Ltd.) Isophthalic acid copolymerized polyethylene terephthalate 2 and the particle master chip 2 were used as raw materials for the supporting layer (B layer), and the respective layers were mixed so as to have the composition shown in Table 2, and the resulting mixture was introduced into an extruder, At a melt extrusion temperature of 255 占 폚, and the layer B was passed through a non-woven fabric filter having an average graduation size of 30 占 퐉 at a melt extrusion temperature of 230 占 폚 to form a B layer / A layer / B layer by using a three-layer feed block device, and the sheet was formed into a sheet from the dies while maintaining the laminated state. At this time, the thickness ratio of the B layer / A layer / B layer was adjusted to be 10/80/10 after biaxial stretching by the discharge amount of each extruder. This sheet was further cooled and solidified with a cooling drum having a surface temperature of 25 DEG C to form an unstretched film. The unstretched film was passed through a preheating zone at 73 占 폚 and then a preheating zone at 75 占 폚 and was led to a longitudinal stretching zone maintained at 92 占 폚 and stretched 3.0 times in the longitudinal direction and cooled by a roll group of 25 占 폚. Subsequently, both ends of the film were passed through a preheating zone at 115 캜 while being held by a clip, and were led to a transverse stretching zone maintained at 130 캜 and stretched 3.6 times in the transverse direction. Thereafter, heat treatment at 155 占 폚 for 10 seconds, heat fixation at 200 占 폚 for 10 seconds, and heat treatment at 155 占 폚 for 10 seconds were successively performed in the tenter, and then, at a width filling ratio of 2% Then, both ends of the film were cut out, heat relaxed to 2.5% of paper percentage, and cooled to room temperature to obtain a film having a thickness of 300 탆. Table 2 shows the evaluation results of the obtained film.

[Examples 2-2 to 2-17, Comparative Examples 2-1 to 2-6]

A white reflective film was obtained in the same manner as in Example 2-1 except that the form of the particles and the nonreinforcing resin and the structure of the film were changed as shown in Table 2. [ Table 2 shows the evaluation results of the obtained film. The synthetic calcium carbonate particles used were surface-treated with trimethyl phosphate.

In Example 2-17, the total thickness of the film was 188 탆.

[Examples 2-18]

On one side of the biaxially oriented film obtained in the same manner as in Example 2-1, the coating liquid having the composition shown in the coating solution 1 for forming the above-mentioned bead layer was coated with a direct gravure coating apparatus in an application amount of a wet thickness of 15 g / , And then dried at 100 DEG C in an oven to obtain a white reflective film having a bead layer. Table 2 shows the evaluation results of the obtained film. In the evaluation, the side of the bead layer was used as the reflecting surface.

[Comparative Example 2-7]

A particle master chip was produced in the same manner as in Production Examples 3 and 4 except that barium sulfate particles having an average particle diameter of 0.9 mu m and (D90 - D10) / D50 of 1.4 were used as the void forming agent in place of the calcium carbonate particles, Was obtained in the same manner as in Example 2-1 except that the composition of the white reflecting film was changed as shown in Table 2. Table 2 shows the evaluation results of the obtained film. These barium sulfate particles were obtained by repeating wind power classification.

[Example 3-1]

(Preparation of white reflective film)

The isophthalic acid copolymerized polyethylene terephthalate 1 and the particle master chip 1 obtained above were used as a material for the reflection layer (A layer), and the isophthalic acid copolymerized polyethylene terephthalate 2 and the particle master chip 3 were used as the surface layer (C layer) And each of the layers was mixed so as to have a composition as shown in Table 3. The mixture was passed through an extruder and the A layer was passed through a nonwoven fabric filter having an average graduation size of 30 占 퐉 to obtain a C layer Passed through a nonwoven fabric filter having an average graduation size of 50 탆 and joined at a melt extrusion temperature of 230 캜 using a three-layer feed block device so as to have a layer structure of C layer / A layer / C layer as shown in Table 3, The sheet was formed into a sheet from the dies while maintaining the laminated state. At this time, the thickness ratio of the C layer / A layer / C layer was adjusted to be 10/80/10 after biaxial drawing by the discharge amount of each extruder. This sheet was further cooled and solidified with a cooling drum having a surface temperature of 25 DEG C to form an unstretched film. The unstretched film was passed through a preheating zone at 73 占 폚 and then a preheating zone at 75 占 폚 and was led to a longitudinal stretching zone maintained at 92 占 폚 and stretched 3.0 times in the longitudinal direction and cooled by a roll group of 25 占 폚. Subsequently, both ends of the film were passed through a preheating zone at 115 캜 while being held by a clip, and were led to a transverse stretching zone maintained at 130 캜 and stretched 3.6 times in the transverse direction. Thereafter, heat treatment at 155 占 폚 for 10 seconds, heat fixation at 200 占 폚 for 10 seconds, and heat treatment at 155 占 폚 for 10 seconds were successively performed in the tenter, and then, in a transverse direction at a width filling ratio of 2% Then, both ends of the film were cut out, heat relaxed to 2.5% of paper percentage, and cooled to room temperature to obtain a film having a thickness of 300 탆. Table 3 shows the evaluation results of the obtained film.

[Examples 3-2 to 3-15 and Comparative Examples 3-1 to 3-10]

A white reflective film was obtained in the same manner as in Example 3-1 except that the mode of the particles and the structure of the film were changed as shown in Table 3. Table 3 shows the evaluation results of the obtained film. The synthetic calcium carbonate particles used were surface-treated with trimethyl phosphate.

In Example 3-10, the total thickness of the film was 188 탆.

The surface layer particles used for the surface layer C are shown below. Was used as a particle master chip in the same manner as in Production Example 5.

Particle B: AY-601, manufactured by Tosoh Silica Co., Ltd., which is a coagulated silica, was classified by wind force into particles having an average particle diameter of 5.0 mu m

Particle C: AY-601, manufactured by Tosoh Silica Co., Ltd., which is a coagulated silica, was classified by wind force into particles having an average particle size of 18.2 占 퐉

Particle D: AY-601 manufactured by Tosoh Silica Co., Ltd., which is a coagulated silica, was classified by wind force into particles having an average particle diameter of 35.3 占 퐉

Particle E: AY-601 manufactured by Tosoh Silica Co., Ltd., which is a coagulated silica, was classified by wind force into particles having an average particle size of 1.0 탆

Particle F: AY-601, manufactured by Tosoh Silica Co., Ltd., which is a coagulated silica, was classified by wind force into particles having an average particle size of 52.0 占 퐉

[Comparative Example 3-11]

A particle master chip was produced in the same manner as in Production Example 3, except that barium sulfate particles having an average particle diameter of 0.9 mu m and (D90 - D10) / D50 of 1.4 were used as the void forming agent in place of the calcium carbonate particles, Was changed to that shown in Table 3, a white reflective film was obtained in the same manner as in Example 3-1. Table 3 shows the evaluation results of the obtained film. These barium sulfate particles were obtained by repeating wind power classification.

Industrial availability

The white reflecting film of the present invention can suppress thermal bending due to heat generated from an electric circuit or a light source and from heat and humidity from the use environment even if the white reflecting film is used for a large display while having excellent reflection characteristics. As a result, unevenness in luminance caused by warping of the white reflective film can be suppressed, and therefore, industrial applicability is high.

Claims (9)

As a white reflective film having a reflective layer A,
The reflective layer (A)
a. The content of the calcium carbonate particles is 10 mass% or more and 70 mass% or less with respect to the mass of the thermoplastic resin composition A1, and the thermoplastic resin A is composed of the thermoplastic resin composition A1 containing calcium carbonate particles,
or,
b. And a thermoplastic resin composition A2 containing calcium carbonate particles and an emulsion resin in the thermoplastic resin A. The content of the calcium carbonate particles is 5 mass% or more and 69 mass% or more with respect to the mass of the thermoplastic resin composition A2 % Of the total amount of the calcium carbonate particles and the content of the nonconstituent resin is not less than 1% by mass and not more than 40% by mass with respect to the mass of the thermoplastic resin composition A2, and the total amount of the thermoplastic resin composition A2 Is not less than 10% by mass and not more than 70% by mass with respect to the mass of the composition.
Wherein the calcium carbonate particles have an average particle diameter of 0.1 占 퐉 or more and 1.2 占 퐉 or less and a 10% volume particle diameter D10, a 50% volume particle diameter D50, and a 90% volume particle diameter D90 integrated from the minor diameter side are (D90 - D10) / D50 Lt; / RTI &gt;
A white reflective film for a large display having a reflectance of at least 60%. The method according to claim 1,
The reflective layer A is a. Wherein the content of the calcium carbonate particles is 10 mass% or more and 70 mass% or less with respect to the mass of the thermoplastic resin composition A1, the thermoplastic resin composition A1 containing calcium carbonate particles in the thermoplastic resin A. The method according to claim 1,
B. And a thermoplastic resin composition A2 containing calcium carbonate particles and an emulsion resin in the thermoplastic resin A. The content of the calcium carbonate particles is 5 mass% or more and 69 mass% or more with respect to the mass of the thermoplastic resin composition A2 % Of the total amount of the calcium carbonate particles and the content of the nonconstituent resin is not less than 1% by mass and not more than 40% by mass with respect to the mass of the thermoplastic resin composition A2, and the total amount of the thermoplastic resin composition A2 By mass to 70% by mass with respect to the mass of the white reflective film. 4. The method according to any one of claims 1 to 3,
The reflective layer A, and further the surface layer C on at least one surface thereof,
The surface layer C is composed of a thermoplastic resin composition C containing surface layer particles and the surface layer particles thereof have an average particle diameter of 2.0 mu m or more and 50.0 mu m or less and a content of not less than 3% by volume with respect to the volume of the thermoplastic resin composition C , Not more than 50% by volume. 5. The method according to any one of claims 1 to 4,
Wherein the thermoplastic resin A is a copolymerized polyethylene terephthalate. 6. The method of claim 5,
Wherein the copolymerization amount of the copolymerized polyethylene terephthalate is 1 mol% or more and 20 mol% or less based on 100 mol% of the total acid components of the copolymerized polyethylene terephthalate. 7. The method according to any one of claims 1 to 6,
Wherein the ratio of the thickness of the reflective layer A to the thickness of 100% of the white reflective film is 50% or more. 8. The method according to any one of claims 1 to 7,
Further comprising a support layer (B) comprising thermoplastic resin (B) or thermoplastic resin composition (B). A surface light source using the white reflecting film according to any one of claims 1 to 8.

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